A validation study on RF based two-dimensional cardiac strain estimation

Two-dimensional (2D) cardiac strain rate imaging could provide an angle independent assessment of myocardial deformation. We have previously proposed a method for estimating the 2D strain (rate) tensor. The aim of this study was to validate this methodology in an in-vitro set up. Hereto, five tubular thick-walled tissue mimicking phantoms were fixed in water tank. Varying the intraluminal pressure resulted in a cyclic radial deformation. The 2D strain tensor was calculated from the 2D velocity estimates, obtained using the radio-frequency (RF) tracking. Additionally, micro crystals were implanted on the outer and inner wall of the tube in order to give an independent measurement of the instantaneous radial strain. As expected, the lateral estimates were less accurate than the axial ones but remained within acceptable limits. 2D RF-tracking using a 1D kernel thus allows for an accurate 2D strain estimation.